Brett Kavanaugh was questioned by senators at a confirmation hearing.

US Supreme Court nominee Brett Kavanaugh has rejected repeated requests at a Senate confirmation hearing to reveal his views about a president pardoning himself or being forced to testify in a criminal case.

For a second day, the judge nominated by Donald Trump insisted he fully embraced the importance of judicial independence.

But he refused to provide direct answers to Democrats who wanted him to say whether there are limits on a president’s power to issue pardons, including to himself or in exchange for a bribe.

He also would not say whether he believes the president can be subpoenaed to testify.

“I’m not going to answer hypothetical questions of that sort,” Mr Kavanaugh said in response to a question from Senator Patrick Leahy of Vermont about pardons.

Supreme Court nominee Brett Kavanaugh faced tough questions on the second day of his confirmation hearing (Manuel Balce Ceneta/AP)

Still, he began his long day in the witness chair by declaring that “no one is above the law”.

The Senate Judiciary Committee hearing has strong political overtones ahead of the November congressional elections, but as a practical matter Democrats lack the votes to block Mr Kavanaugh’s confirmation.

They are concerned that Mr Kavanaugh will push the court to the right on abortion, guns and other issues, and that he will side with President Trump in cases stemming from special counsel Robert Mueller’s investigation of Russian interference in the 2016 election and possible ties to the Trump campaign.

The 53-year-old appellate judge answered cautiously when asked about most of those matters, refusing an invitation from Democratic Senator Richard Blumenthal of Connecticut to pledge to step aside from any Supreme Court cases dealing with Mr Trump and Mr Mueller’s investigation.

Mr Kavanaugh’s most uncomfortable moment may have come near the end of nearly 12 hours in the witness chair, when Democratic Senator Kamala Harris asked whether he had discussed the investigation with anyone at a law firm founded by Marc Kasowitz, a one-time lawyer for Mr Trump.

Mr Kavanaugh said he could not recall any conversations, but asked for a list of lawyers at the firm.

Ms Harris said she thought Mr Kavanaugh had a name in mind but did not want to reveal it. She promised to follow up, amid Republican complaints that she was being unfair.

Protesters continued their efforts to interrupt the hearings, but senators basically ignored their shouts as they were removed by police.

A protester was removed from the hearing in Washington (Manuel Balce Ceneta/AP)

US Capitol Police said 66 people were removed from the committee room on Wednesday and charged with disorderly conduct. Six more at a different Senate office building were charged with crowding, obstructing or incommoding.

Democrats also persisted with their complaints that they were being denied access to records from Mr Kavanaugh’s time in the George W Bush White House.

Mr Trump said he had been watching the hearings and thought the Democrats were “grasping at straws” in questioning the man he chose to replace retired Justice Anthony Kennedy.

He said he “saw some incredible answers to very complex questions”.

The committee’s top Democrat, Dianne Feinstein of California, disagreed. “He’s not being very specific,” she said during a break in the proceedings.

The Democrats were not the only ones who recognised the importance of questions about Mr Trump and the Russia investigation.

Committee Chairman Chuck Grassley, an Iowa Republican, asked Mr Kavanaugh right away whether he would be independent from the president who chose him for highly prestigious lifetime position.

Mr Kavanaugh said, “The first thing that makes a good judge is independence, not being swayed by political or public pressure.”

He cited historic cases, including the Brown v Board of Education ruling that desegregated schools and the US v Nixon decision that compelled the president to turn over the Watergate tapes — a ruling Mr Kavanaugh had previously questioned.

“That takes some backbone,” he said of the justices who decided those cases.

But when asked more specific questions, including whether a president can be required to respond to a subpoena, Mr Kavanaugh said, “I can’t give you an answer on that hypothetical question.”

The Supreme Court has never answered that question, and it is among the potentially most important since Mr Trump could face a subpoena from special counsel Mr Mueller.

Senator Amy Klobuchar, a Minnesota Democrat, asked whether a president could be criminally investigated or indicted.

Mr Kavanaugh again said he had never taken a position on those issues, though he did write in a 1998 article that impeachment may be the only way to hold a president accountable while in office.

“The Constitution itself seems to dictate, in addition, that congressional investigation must take place in lieu of criminal investigation when the president is the subject of investigation, and that criminal prosecution can occur only after the president has left office,” he wrote in the Georgetown Law Review.